There are limited data in the literature concerning in vivo effects of dietary fat supplementation on enteric CH4 emissions from lactating dairy cows.

The purpose of this experiment was to evaluate four dietary treatments designated as control (CON), brewers grains (BG), hominy meal and cold-pressed canola (HCC) and hominy meal only (HM) for their effects on CH4 emissions and milk production.

Trial setup

Sixteen late lactation Holstein cows were used in pairs, in a double 4 × 4 Latin square experiment with the four dietary treatments fed as total mixed rations over 24 d treatment periods.

For the BG, HCC and HM diets, part of the cracked wheat and solvent extracted canola was substituted with the designated fat supplement so that the resulting diets contained 51, 52 and 65 g total fat/kg DM respectively.

Results

Fat supplementation did not influence DM intake and there were only small positive effects on milk yield and negative effects on concentrations of milk fat and milk protein.

Combining results of this investigation with data from the literature, the scientists conclude that for each increase of 10 g/kg DM in dietary lipid concentration, enteric emissions are reduced by 0.79 g CH4/kg DM intake or ∼3.5% thereby allowing estimation of the magnitude of enteric CH4 abatement based on dietary fat supplementation.